Mounting bigger fans don't cure a cooling problem.

Make sure your rad, the water pump, the thermostate are in a good condition. Check the antifreeze. AND most important: Check how your engine's running. When it's too lean, it also will be getting hot!

I'd recommend:

1. Check management / fuelling
2. Use a new (maybe alloy) rad
3. Use a 82° (RS1600i, maybe Cosworth and FRP also?) thermostate
4. Use a new water pump
5. Get rid of the standard oil cooler, get a new oil/air one!